TROPICAL DEPRESSION IVETTE DISCUSSION NUMBER 22
NWS NATIONAL HURRICANE CENTER MIAMI FL EP102016
800 PM PDT SUN AUG 07 2016
The deep convection that was near the center of Ivette earlier in
the day has been sheared away, with the closest area of
thunderstorms about 80 n mi northeast of the center. This is
the result of 20-25 kt of southwesterly shear. A pair of ASCAT
passes from several hours ago showed maximum winds near 35 kt in
the northern portion of the circulation. Assuming some spin down
since that time, the initial intensity is lowered to 30 kt, making
Ivette a tropical depression. This intensity estimate is also in
agreement with the Dvorak classifications from TAFB and SAB.
Although some deep convection could return near the center,
continued strong southwesterly shear and dry air should limit the
organization of this activity and cause weakening. Ivette is
expected to degenerate to a remnant low on Monday, and dissipate to
the east of the Hawaiian Islands in 2 to 3 days.
The shallow cyclone has turned westward in the low-level flow. A
general westward motion at about 10 kt is expected until the
cyclone dissipates. The NHC official track forecast lies on the
southern edge of the guidance, and is adjusted to the south of the
previous prediction.
The next advisory on Ivette will be issued by the Central Pacific
Hurricane Center in Honolulu, Hawaii.
TROPICAL STORM IVETTE DISCUSSION NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL EP102016
200 AM PDT WED AUG 03 2016
The cloud pattern of the tropical cyclone has gradually improved
since yesterday afternoon, with an increase in banding over the
western portion of the circulation. Microwave images show
that the center is located near the northeastern edge of the
convective band due to moderate northeasterly shear, but a new
burst of deep convection has very recently developed near the
estimate center location. Although earlier ASCAT data showed
maximum winds around 30 kt, the recent improvement in organization
and Dvorak T-numbers from TAFB and SAB support increasing the
initial intensity to 35 kt. Ivette becomes the ninth tropical storm
to form in the eastern Pacific basin since July 2nd.
Ivette is moving westward at an atypically fast speed of 17 kt.
A strong subtropical ridge to the north of the cyclone should keep
it moving westward to west-northwestward during the next several
days, with the forward speed gradually decreasing as it nears the
western portion of the ridge. By late in the period, Ivette should
turn west-northwestward and decelerate further as a break in the
ridge develops between 140W and 150W. The updated NHC track is
similar to the previous advisory, but has been nudged southward to
be closer to the multi-model consensus.
The northeasterly shear affecting the tropical cyclone is forecast
to decrease during the next 24 hours. This should allow
strengthening while Ivette moves over warm water and remains
in a moist environment. The NHC intensity forecast is above the
statistical guidance and is closer to the HWRF model, which brings
Ivette to hurricane strength in a couple of days. Increasing
southwesterly shear, slightly cooler SSTs, and drier mid-level air
should cause gradual weakening late in the period.
TROPICAL DEPRESSION TEN-E DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL EP102016
200 PM PDT TUE AUG 02 2016
Satellite images indicate the area of low pressure well southwest
of mainland Mexico has become better organized. ASCAT data
indicate the center is fairly well defined, with curved banding
features forming around the surface center. Thus tropical cyclone
advisories are being initiated on this system. Dvorak estimates and
the ASCAT data support an initial wind speed of 30 kt. Gradual
strengthening is forecast for the next few days while the cyclone
remains over warm water, with weak-to-moderate shear and high mid-
level humidity. The official forecast is a bit higher than the
model consensus, since most of the guidance has had a low bias this
season.
ASCAT and microwave data give a relatively confident initial motion
of 290/15. A strong subtropical ridge over the eastern Pacific is
expected to steer the cyclone relatively quickly to the west over
the next few days. The ridge is forecast to weaken on days 4 and 5,
which should cause a decrease in forward speed while the system
approaches the central Pacific. Track guidance is in remarkable
agreement for the first advisory, and the official forecast is near,
but slightly faster than, the model consensus.
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